Gag, but not dgp41, is protected from trypsin digestion, suggesting the proteins are organized into enveloped VLPs. Following density centrifugation, the Gag/dgp41 enriched fraction was subjected to proteolysis in the presence or absence of 1% Triton X-100, subjected to SDS-PAGE and immunoblotting. (A) Detection with anti-p24 antiserum. (B) Detection with 2F5 monoclonal Ab against MPER. The first lane (from left) contains proteins from non-infiltrated wild type plant extract. The remaining lanes contain VLP enriched samples from a transgenic Gag-expressing plant, incubated as indicated with or without Triton X-100 and/or trypsin.